HSR19-106: Association Between Pathological Complete Responses and Long-Term Survival Outcomes Among Triple-Negative Breast Cancer Patients Receiving Neoadjuvant Chemotherapy

Objective: Pathological complete response (pCR) has been a commonly used endpoint in neoadjuvant trials for breast cancer (BC). A pooled analysis of 12 neoadjuvant BC trials by Cortazar et al (2014) reported a positive association between pCR and long-term survival outcomes among patients with general BC and certain subtypes including triple negative BC (TNBC). To update and extend the evidence to assess the association of pCR and survival outcomes in TNBC, this study reviewed and summarized cohort studies and recent clinical trials in the literature. Methods: English publications reporting association between pCR and survival outcomes among TNBC patients receiving neoadjuvant chemotherapy were searched in MEDLINE, EMBASE, Cochrane CENTRAL, and Northern Light Sciences Conference Abstracts. Full-text publications from all years and conference abstracts since year 2016 were identified. Relevant clinical trials, real-world evidence (RWE) studies, and meta-analyses were included for review and extraction. Results: Of total 1,880 publications retrieved, 35 reported association between pCR and survival outcomes for neoadjuvant TNBC (9 clinical trials, 21 RWE studies, and 5 pooled/meta-analyses). The sample size of TNBC patients varied between 25 and 1,645. Different pCR definitions were used across studies, of which absence of tumor in the breast and axillary nodes was most common (N=29). The prognostic impact of pCR was evaluated for multiple survival outcomes: overall survival (OS; N=19), disease-free survival (DFS; N=14), relapse-free survival (RFS; N=7), event-free survival (N=5), distant DFS (N = 4), and local RFS (N=2). Kaplan-Meier analysis was used to assess the association between pCR and these outcomes in 31 studies. Clear separation of survival curves in favor of pCR was observed in all the studies. Log-rank tests were conducted in 18 studies, and statistically significant association was reported in majority of them, except for 1 RWE study with small sample size (N=35) and 1 pooled analysis with a different pCR definition (absence of tumor in the breast) than most of the others. Cox proportional hazards model was used in 17 studies, wherein hazard ratios of survival outcomes comparing pCR vs non-pCR ranged from 0.08 to 0.53. Conclusions: Despite divergent study designs and pCR definitions, evidence from both clinical and real-world settings consistently suggest that pCR is a strong predictor of OS and other survival outcomes among TNBC patients.